Method of making composite articles



Nov. '1, 1938. F. H. BENGE METHOD OF MAKING COMPOSITE ARTICLES Filed July 8, 1953' Patented Nov. 1, 1938 v UNITED STATES UMETHOD OF MAKING COMPOSITE ARTI- CLES Frank H. Benge, Norristown,

Pa., assignor to Continental-Diamond Fibre Company, Newark, Del., a corporation of Delaware Original application August 13, 1935, Serial 'No. 35,994. Divided and this application July 8, 1936, Serial No. 89,677

3 Claims.

This invention relates to a novel method of making composite articles and more particularly composite gears or like elements formed of metallic and non-metallic materials. The present application is a division of copending application, Serial No. 35,994, filed August 13, 1935. The principal object of the present invention is to provide a novel method of making the improved gear claimed in the said ccpending application. 7

A more specific object of the present invention is to provide a gear having a composite'rim formed of complementary metallic and nonmetallic parts wherein the parts are caused to fit snugly and become firmly secured to one another.

A further object of the present invention is to provide a gear of this character wherein a metallic rim is caused to contract tightly about a nonmetallic part by expanding the metallic rim during manufacture of the gear to cause contraction of the rim during subsequent shrinkage of the non-metallic part. 7

The invention may be clearly understood by reference to the accompanying drawing illustrating the principal steps of the method.

In the accompanying drawing:

Fig. l is a sectional view illustrating the initial step in the molding of a gear according to the present invention;

Fig. 2 is a similar View illustrating the next step in the process and showing the expansion of the metallic rim; and

Fig.3 is a similar view illustrating the final step and showing the contraction of the metallic rim about the shrunkennon-metallic part.

As set forth in the copending parent application above mentioned, the gearto which the present invention is directed comprises a nonmetallic body and a metallic rim. The non metallic body may be formed of any suitable material such as Bakelite, hard rubber, hard wood of the non-metallic body of the same material, these portions of the gear being formed integrally in accordance with the method described hereinafter. The metallic rim may be formed of any suitable metal having the desired strength. Preferably steel is employed in the formation of this rim.

Referring now to the drawing,.in the manufacture of'the gear a solid steel ring I is placed in' a mold 2 whose inner diameter is larger than the outer diameter of the steel rim by a predetermined amount. The rim l is preferably provided with one or more annular inner recesses, such as shown at 3, for reasons set forth in the copending parent application but which need not be gone into here. It sufiices to state here that this structure provides a composite metallic and non-metallic rim or toothed portion on the finished gear. In the employment of the preferred' materials above mentioned, the mold 2 has an inner diameter which is one-thirty-second ($5) of an inch larger than the outer diameter of the steel rim l. The mold members 4 and 5 have complementary surfaces 6 and l, respectively, which conform to the shape of the nonmetallic surfaces desired on the finished gear. A metallic ring 8 is placed within the mold upon the steel rim i. This ring serves as a guide for the mold part 5 and also serves to keep the fibrous material away from the upper surface of the steel rim i. If a metallic bushing i9 is employed, it may be inserted in the mold, as clearly shown in Fig. 1. A central pin I l serves to guide the movable mold part 5 and also serves to keep the fibrous material from falling into the interior of the bushing Hi.

. With the above-mentioned parts in place, the interspersed pieces l2 of fibrous or fabric material are placed in the mold in predetermined quantity, as shown in Fig. 1, these fibrous pieces having been impregnated with phenol formaldehyde resin in its initial stage in which it is fusible. These resin-impregnated fibrous pieces may vary widely in size, generally varying from one eighth inch at the smallest Width up to one inch at the greatest width. The resin associated with the fibrous pieces varies from 43% to 60%, the latter figure being preferable and at times powdered resin may be added if it is desired or necessary.

After the resin-impregnated fibrous material has been placed in the mold, the movable mold part 5 is lowered under pressure, which may be in the neighborhood of 2500 lbs. per square inch. Due to the resilience of the steel rim l, the pressure expands the rim against the mold wall, as

i illustrated in Fig. 2,thus placing the rim under tension within its. elastic limit. The resin-impregnated fibrous material enters and fills the 7' recess 3 as clearly shown. The resin-impregnated fibrous'material is then subjected to a temperature'of between 360 and 400 F. at

facture of the ordinary composite gear, the

increased cost is fully warranted by the improved results obtained.

7 Although the invention has beencdescribed with reference to the preferred method of making the product, it is obviously susceptible to the same time that the pressure is applied to convert the resin to its final and infusible stage. I 'he time of heating depends upon the size of the gear andrmay be in the neighborhood of thirty minutes or more. The curing'is carried out at a temperature and for a time. sufiicient to 'convert the resin into its finalstage in which it is infusible and insoluble. During this heating process, the conversion or curing of theresinous binder causes the resin-impregnated fibrous 7 material to contractor shrink. By virtue of the tension'Of the steel rim, the rim likewise con-' tractsso that it is maintained in snug engage-, V 'ment with the fibrous material in the finished f'product. 'In Fig. 3,'the movable mold part S'has' been raised slightly. following the conversion process, and the contraction of thesteel rim against the shrunken or contracted fibrous material is illustrated; The reason; for having the mold larger than the steel rim to permit expansion of the rim' will now be apparent. .This

methodinsures a snug'fit and firm b'ondage of the steel rim about the fibrous material. It will.

,be obvious that in anyinstance the .expansion of the 'metal rim should be predetermined ,for

the'particular non-metallic material used, within the limit of elasticity of the metal; This pre- 'sumes or course a non-'metallic material which contracts or shrinksduring'the conversion prooes's.'

After .the'composite article is removed from the mold, the teeth maybe'cut' in the composite rim of the gear to provide the structure disclosed and claimedin the copending parent application. The teethmay be cutin any suitable man ner known to the art since the product has the necessary machining qualities and strength. 7

V Agear'con'structed in accordance with the invention'is far superior to the ordinary composite gear made entirely of non-metallic-material and yet retains the desired qualities of such gear,

r such as quiet operation and economy of produc- =tion Comparative tests have shown that the gear .formed' by this invention will outlast the :ordinary composite gear in the ratio of approximately 20 to 1. In a, specific case, under. a certain test load, an ordinary composite gear ran "for only five hours beforefailure, whereas a gear constructed according to the invention showed no indications 10f failure after one hundred hours. The cost of manufacture of the present gear is not much greater than the cost of. manuskilled in the art.

modifications such as mayoccur to persons I claim:

A method of making a compositeimachine.

element, such as a gear, which comprises placing a metallic rim having at least one inneranterspersed pieces or fibrous material 1 impregnated with synthetic resin in its initial stage in said mold within the rim fto form thebody of ,said gear," applying pressure to said fmaterial" nular' recess in a mold of predetermined dianivetergreater than that of the rim, depositing in-.

suflicient to form the said body with a portion thereof extending into said recess and to expand placing said rim under tension, andconverting the said resin to its final hardened stage caussaid rim outward against, the mold wall thus ing the resinimpregnated fibrous material to V shrink, whereby the tension of said metallic rim causes it to contract tightly about said body.

2. .A method of forming a composite fibre and metal gear, which comprises placing a metallic rim ina mold of predetermined diameter greater than that of the rim, depositing interspersed pieces of fibrous material impregnated with syn- V 7 thetio resin in its initial stage in said mold within the rim to. form the body of the gear, app ing. pressure to said materialsufiicient'to form V the said body and to expand said rim against the metal gear, which comprises placing a metallic.

i rim in a mold of predetermined diameter great a er than that of therim, depositing interspersed pieces of fibrous material impregnated with phenolic resin in its fusible stage in said mold -within.the rim to form the body of the gear,

applying pressure to said material sumcient to form the said body and to expand" said rim against the 'mold wall thus placing said rim?- ,under tension, and converting .the said resin to its final insoluble stage causingthe resin-im pregnated fibrous material "to shrink,- whereby the tension of said metallic rim causes it to 0011- tract tightly about said body.

BENGE. 

